What are super-computers?

Last week, the Department of Energy in the United States announced that it is going to build the world’s most powerful computer, a super-computer. The United States has always been a pioneer of technology, however here in the Lambourn Valley there are people who have been involved in the development and deployment of super-computers. This article has been contributed by Alistair Mills, who worked for Cray Research, the company which is going to build the super-computer. Here he tells the story …

The Department of Energy has announced that it will spend $600 million on a new super-computer, to be named Frontier. The machine will enable “extreme scale scientific endeavours” to lead to “breakthroughs in scientific discovery, energy assurance, economic competitiveness and national security“. Frontier will be located at Oak Ridge National Laboratory in Tennessee. It is only two months ago that the Department of Energy made a similar announcement that it will spend $500 million on a computer to be called Aurora, which will be located at Argonne National Laboratory in Illinois. In this article, I shall describe super-computers and why they are important. [1, 2]

A super-computer is not a super games-machine. You may imagine that a super-computer is a big version of the computers you are used to using, and in some sense this is true. It is built by assembling many inexpensive components into a single system. Systems such as Frontier and Aurora contain a million processors and a million storage devices and a very high capacity network which binds them together into a single image.

A simple definition of a super-computer is one which is so large that no-one would consider installing one at home! A normal home uses electricity to power many services, such as heating, cooking, lighting, entertainment, telephones, computers and home networking. However, the average power use is about 1 Kilowatt. The energy needed for Frontier or Aurora is 10,000 Kilowatts. This is not peak use, this is 24 hours per day, 365 days per year! This is enough energy to power a town the size of Newbury! These computers are housed in buildings which are designed for the purpose; the floor space is considerable, and so too is the need for cooling, ventilation, power supply, and other services. If Bill Gates decided he wanted a super-computer at home, he would have to give up his seven bedrooms, ten bathrooms, six kitchens and six fireplaces. [3, 4]

Another way to consider a super-computer is to compare it to other large machines. A jumbo jet is an amazing machine; it can fly hundreds of people to anywhere on earth in under a day. However, almost all jumbo jets belong to airlines and they are continuously flying paying passengers between the large airports of the world. Only a few heads of states have a personal jumbo jet; these aircraft are part of the diplomatic apparatus of the state; when Sheik Mohammed wants to help the victims of a natural disaster, he sends his plane full of doctors and nurses; when he wants to have fun with his friends, he has a yacht. However, he probably sends his jumbo jet to pick them up! Even Sheik Mohamed does not have a personal super-computer. [5]

A super-computer is a very large capacity computer which can process a very large amount of data quickly enough for the results to be useful. An example of an application is weather forecasting. The largest computers in the UK today are in the Met Office in Exeter and the European Centre for Medium Range Weather Forecasts in Reading. [6, 7]

Accurate weather forecasting requires collecting a lot of data from all over the world, from various observation systems including satellites, aircraft in flight, ground stations, weather balloons and ships at sea. To be useful, the forecast must be ready before the weather arrives. For the last two decades, weather forecasts use a method call ensemble forecasting. This method requires many forecasts using small changes to the data and observing the spread of the results. When there is a small spread of results, the forecast is deemed reliable; a large spread indicates that the forecast is less reliable. When the Met Office provides a forecast for the week ahead, the forecaster is sometimes quite confident about what will happen; other times, the forecaster uses vague terms. In our time, there is a lot of interest in climatic studies. This is rather like a forecast for fifty years, but there is very little data about the future. These studies require very large computers. [8]

The father of the super-computer was Seymour Cray. Seymour was an engineer who came from Wisconsin. Between 1960 and 1990, the answer to the question, who designs the world’s most powerful computers, was Seymour Cray. Seymour worked for the leader in large computers in the 1960s before founding his own company called Cray Research in 1972. Seymour died in 1996. To avoid confusion, he is usually referred to as Seymour, and his business is referred to as Cray. Seymour was a rather reclusive engineer who enjoyed designing computers. He always thought it was the work of others to make a corporation which could build, sell and support super-computers. [9, 10]

There is an organisation called Top500 which keeps records of the top 500 computers in the world. Twice per year it publishes a new list of the computers. These lists are quite detailed, and there is a web site which allows you to download the lists for the last twenty years. Anyone who likes playing with data and spreadsheets can spend a long time with this data; if you like this kind of thing, you will probably like working with super-computers too. [11]

This part of our country is home to many research and development organisations, such as:

Weather forecasting and climate studies, at ECMWF in Reading;

Atomic energy at the Harwell Laboratory near Abingdon;

Fusion energy at the Culham Laboratory near Abingdon;

Scientific research at the Rutherford Laboratory near Abingdon;

Academic research at the Universities of Oxford and Reading;

Defence and security research at AWE near Newbury;

Weather forecasting at the Met Office, formerly in Bracknell, now in Exeter.

In the UK today, there are 20 computers which are in the list of the top 500 computers. These computers are owned and operated by these organisations. [12, 13, 14, 15]

Every decade, the performance of the largest computers increases one thousand-fold. This increase in performance is remarkable and has made it possible to do things easily and cheaply which were not possible just a few years ago. Our smart phones are not super-computers, but they are products which have evolved from the pioneering work of building super-computers. The next time you access the weather forecast on your smart phone, the information is the result of data processing on one of the world’s largest computers.